안녕하세요. 최용일입니다.

PixelFormat만 바꾸어주시면 여러가지 칼러로 변환됩니다. 물론 만족할 만한 결과를 얻을려면 여러가지 처리를 해주어야 겠지만요...

    Bitmap := TBitmap.Create;
    Bitmap.LoadFromFile('Ctest.bmp');
    Bitmap.PixelFormat := pf4bit; // 16칼라로...
    Bitmap.SaveToFile('C:test16.bmp');
    Bitmap.Free;

아래와 같이 프린트 해보세요...

var
    Bitmap: TBitmap;
    Info: PBitmapInfo;
    InfoSize: DWORD;
    Image: Pointer;
    ImageSize: DWORD;
    Bits: HBITMAP;
    DIBWidth, DIBHeight: Longint;
    PrintWidth, PrintHeight: Longint;
begin
    Printer.BeginDoc;
    try
        Bitmap := TBitmap.Create;
        Bitmap.LoadFromFile('D:ProjectsWebCall(New)Testtest.bmp');
        Bitmap.PixelFormat := pf4bit;
        try
            with Printer do
            begin
                Bits := Bitmap.Handle;
                GetDIBSizes(Bits, InfoSize, ImageSize);
                Info := AllocMem(InfoSize);
                try
                    Image := AllocMem(ImageSize);
                    try
                        GetDIB(Bits, 0, Info^, Image^);
                        DIBWidth := Info^.bmiHeader.biWidth;
                        DIBHeight := Info^.bmiHeader.biHeight;
                        PrintWidth := MulDiv(DIBWidth, GetDeviceCaps(Handle, LOGPIXELSX), PixelsPerInch);
                        PrintHeight := MulDiv(DIBHeight, GetDeviceCaps(Handle, LOGPIXELSY), PixelsPerInch);
                        StretchDIBits(Canvas.Handle, 0, 0, PrintWidth, PrintHeight, 0, 0,
                        DIBWidth, DIBHeight, Image, Info^, DIB_RGB_COLORS, SRCCOPY);
                    finally
                        FreeMem(Image, ImageSize);
                    end;
                finally
                    FreeMem(Info, InfoSize);
              end;
            end;
        finally
            Bitmap.Free;
        end;
    finally
        Printer.EndDoc;
    end;

end;

^^ 항상 즐코하세요...